"There are countries with whom we're negotiating and the question becomes the obvious one that you think, as a matter of business, how does this work? So what he has decided to do is to pause the imposition of the tariffs with respect to those countries," Lighthizer said, as quoted by the CNBC broadcaster.
According to South Korean Trade Minister Kim Hyun-chong, the exemption is effective until late April.
Earlier in March, US President Donald Trump leveraged national security concerns to issue an order that imposes 25 percent tariffs on steel imports and 10 percent duties on aluminum imports. The measures will become effective on Friday.
READ MORE: US Begins Taking Tariff Exemption Requests for Steel, Aluminum Products
At the same time, the United States suggested exemptions for some allies if they can prove their goods do not pose threat to national security. Washington’s trade move is being criticized for posing a threat to global economic relations and potentially leading to a major trade war.